In piping and pipeline repair, it is frequently necessary to close an opening in a tubular member or vessel either temporarily, semi-permanently or, in the case of the present invention, permanently by way of a completion plug. The opening in the tubular member is usually permanently closed when a valve is not required (or no longer required) and is not desirable. One example of the use of a completion plug arises when a hot tap is made into a pipeline or vessel through a fitting connected to the pipeline or vessel.
In the typical hot tapping application, a fitting—usually in the form of a flange—is welded on the exterior of a pipe that has flowing gas or liquid under pressure. A valve is then secured to the flange and a hot tapping machine is secured to the valve. By use of specialized equipment, a hole can then be drilled through the wall of the pipe while gas or liquid continues to flow through it. This provides access to the interior of the pipe, such as for inserting equipment to temporary block flow through the pipe while repairs are being made. After repairs are complete, a threaded or non-threaded completion plug is typically inserted as a temporary seal so that the equipment may be reclaimed.
Threaded completion plugs are usually manually inserted into the flange and then a wrench or driver is inserted into a recess in the upper end of the plug so that the plug can be threadably rotated into a sealed position. Non-threaded closures typically include a mechanism by which a portion of the closure can be radially outwardly extended into an internal circumferential groove in the flange. Because neither type of closure provides an adequate permanent seal, after the equipment is reclaimed a blind flange must be installed as the final, permanent seal. A completion plug made according to this invention and a method for its use provides both the temporary seal and the final permanent seal.